Owing to a recently rapid development and popularity of Internet technology, Internet has been easily used by anyone at present so that Internet user population has explosively increased, and Internet access methods and ways to use a network tend to have been complicated and diverse.
In a current price system in which it currently costs about 30,000 won to connect one floating public IP (Internet IP) address for Internet access, and it additionally costs more than 10,000 won for additional IP, it is uneconomical to assign a plurality of public IP addresses to a plurality of hosts, and there is a difficulty in failing to solve a depletion and shortage of limited IP addresses.
Therefore, to solve these problems, there have been recently many cases in which a network sharing device such as an IP sharer is used to form a network address translation (NAT) at one public IP such that a plurality of client subscribers concurrently use a network. Such sharing formation or system is frequently used in a normal environment using network sharing as well as companies.
However, network traffic overload and hacking, virus, or worm having a malicious object due to an increase in thoughtless network sharing become problems, which make it difficult to grasp a line availability status and sharing rate of a service provider and cause economical loss such as new facility expansion cost due to an increase in the corresponding network traffic, investment loss, and maintenance cost, and thus a problem in that line availability right is not uniformly provided to subscribers occurs.
Accordingly, to track a user who incurs the problem of the thoughtless network sharing, although it is important to settle expense loss by obtaining an actual IP address of the user, catching and analyzing the number of clients actually available for each line, establishing a management policy such as a selective allowance or shutoff with respect to the corresponding line, and separately charging loss expenses due to the traffic overload, no practical and detailed solution or method has not yet been proposed.